Submission #1191590

#	Time	Username	Problem	Language	Result	Execution time	Memory
1191590		12345678	Min-max tree (BOI18_minmaxtree)	C++20	100 / 100	190 ms	36312 KiB

minmaxtree

#include <bits/stdc++.h>

using namespace std;

const int nx=7e4+5, kx=17;

int n, k, u[nx], v[nx], x, y, w[nx], lvl[nx], pa[nx][kx], mn[nx], mx[nx], sz[nx];
char opr;
vector<int> d[nx], addmn[nx], remmn[nx], addmx[nx], remmx[nx], adj[nx];
multiset<pair<int ,int>> msmx, msmn;

int lca(int u, int v)
{
    if (lvl[u]>lvl[v]) swap(u, v);
    for (int i=kx-1; i>=0; i--) if (lvl[pa[v][i]]>=lvl[u]) v=pa[v][i];
    if (u==v) return u;
    for (int i=kx-1; i>=0; i--) if (pa[u][i]!=pa[v][i]) u=pa[u][i], v=pa[v][i];
    return pa[u][0];
}

void dfs(int u, int p)
{
    lvl[u]=lvl[p]+1;
    pa[u][0]=p;
    for (int i=1; i<kx; i++) pa[u][i]=pa[pa[u][i-1]][i-1];
    for (auto v:d[u]) if (v!=p) dfs(v, u);
}

void dfssz(int u, int p)
{
    sz[u]=1+addmn[u].size()+remmn[u].size()+addmx[u].size()+remmx[u].size();
    for (auto v:d[u]) if (v!=p) dfssz(v, u), sz[u]+=sz[v];
}

void dfsadd(int u, int p)
{
    for (auto v:d[u]) if (v!=p) dfsadd(v, u);
    for (auto x:addmn[u]) msmn.insert({w[x], x});
    for (auto x:remmn[u]) msmn.erase(msmn.find({w[x], x}));
    for (auto x:addmx[u]) msmx.insert({w[x], x});
    for (auto x:remmx[u]) msmx.erase(msmx.find({w[x], x}));
}

void sack(int u, int p, bool rem)
{
    pair<int, int> hv;
    for (auto v:d[u]) if (v!=p) hv=max(hv, {sz[v], v});
    for (auto v:d[u]) if (v!=p&&v!=hv.second) sack(v, u, 1);
    if (hv.second) sack(hv.second, u, 0);
    for (auto v:d[u]) if (v!=p&&v!=hv.second) dfsadd(v, u);
    for (auto x:addmn[u]) msmn.insert({w[x], x});
    for (auto x:remmn[u]) msmn.erase(msmn.find({w[x], x}));
    for (auto x:addmx[u]) msmx.insert({w[x], x});
    for (auto x:remmx[u]) msmx.erase(msmx.find({w[x], x}));
    mx[u]=mn[u]=0;
    if (!msmx.empty()) mx[u]=msmx.begin()->first, adj[u].push_back(msmx.begin()->second);
    if (!msmn.empty()) mn[u]=prev(msmn.end())->first, adj[u].push_back(prev(msmn.end())->second);
    if (rem) msmx.clear(), msmn.clear();
}

struct hobcroftkarp
{
    int l[nx], r[nx], cnt, lvl[nx], ptr[nx];
    void bfs()
    {
        queue<int> q;
        for (int i=2; i<=n; i++) if (!l[i]) lvl[i]=0, q.push(i);
        while (!q.empty())
        {
            auto u=q.front();
            q.pop();
            for (auto v:adj[u]) if (r[v]&&lvl[r[v]]==-1) lvl[r[v]]=lvl[u]+1, q.push(r[v]);
        }
    }
    bool dfs(int u)
    {
        for (; ptr[u] < adj[u].size(); ptr[u]++)
        {
            int v=adj[u][ptr[u]];
            if (!r[v]||(lvl[r[v]]==lvl[u]+1&&dfs(r[v])))
            {
                l[u]=v;
                r[v]=u;
                return 1;
            }
        }
        return 0;
    }
    void findmatching()
    {
        while (1)
        {
            for (int i=1; i<=n; i++) lvl[i]=-1, ptr[i]=0;
            cnt=0;
            bfs();
            for (int i=2; i<=n; i++) if (!l[i]&&dfs(i)) cnt++;
            //cout<<cnt<<'\n';
            if (cnt==0) break;
        }
    }
} m;

int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n;
    for (int i=1; i<n; i++) cin>>u[i]>>v[i], d[u[i]].push_back(v[i]), d[v[i]].push_back(u[i]);
    dfs(1, 1);
    cin>>k;
    for (int i=1; i<=k; i++) 
    {
        cin>>opr>>x>>y>>w[i];
        int l=lca(x, y);
        if (opr=='M') addmx[x].push_back(i), addmx[y].push_back(i), remmx[l].push_back(i), remmx[l].push_back(i);
        else addmn[x].push_back(i), addmn[y].push_back(i), remmn[l].push_back(i), remmn[l].push_back(i);
    }
    dfssz(1, 1);
    sack(1, 1, 0);
    m.findmatching();
    for (int i=2; i<=n; i++)
    {
        int cur=i;
        if (m.l[cur]) cout<<i<<' '<<pa[i][0]<<' '<<w[m.l[cur]]<<'\n';
        else cout<<i<<' '<<pa[i][0]<<' '<<mn[cur]<<'\n';
    }
}

• Subtask 1: 7 / 7
• Subtask 2: 22 / 22
• Subtask 3: 29 / 29
• Subtask 4: 42 / 42